scsi: fcoe: Fix mismatched fcoe_wwn_from_mac declaration

scsi: fcoe: Fix mismatched fcoe_wwn_from_mac declaration

An old cleanup changed the array size from MAX_ADDR_LEN to unspecified in
the declaration, but now gcc-11 warns about this:

drivers/scsi/fcoe/fcoe_ctlr.c:1972:37: error: argument 1 of type ‘unsigned char[32]’ with mismatched bound [-Werror=array-parameter=]
 1972 | u64 fcoe_wwn_from_mac(unsigned char mac[MAX_ADDR_LEN],
      |                       ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
In file included from /git/arm-soc/drivers/scsi/fcoe/fcoe_ctlr.c:33:
include/scsi/libfcoe.h:252:37: note: previously declared as ‘unsigned char[]’
  252 | u64 fcoe_wwn_from_mac(unsigned char mac[], unsigned int, unsigned int);
      |                       ~~~~~~~~~~~~~~^~~~~

Change the type back to what the function definition uses.

Link: https://lore.kernel.org/r/20210322164702.957810-1-arnd@kernel.org
Fixes: fdd78027fd47 ("[SCSI] fcoe: cleans up libfcoe.h and adds fcoe.h for fcoe module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>